Method of manufacturing a hollow metal part by use of high energy means



3,165,404 L. PART Jan. 12, 1965 R. w. CALLENDER METHOD OF MANUFACTURING A HOLLOW META BY USE OF HIGH ENERGY MEANS Filed Oct.

I N VENTOE Pa 4,014 (da 1. ENDEJ? JQFfO EN Eg/ United States Patent METHOD OF MANUFACTURING A HOLLGW METAL PART BY USE (IF HIGH ENERGY MEANS Ralph W. Callender, Hinstlale, Ilk, assignor to International Harvester (Iompany, Chicago, Ill., a corporation of New Jersey Filed Oct. 2, 1961, Ser. No. 143,022 9 Claims. (@1- 75--214) This invention relates to the art of powder metallurgy. More specifically this invention relates to a process of making hollow powdered metal parts by the utilization of an explosive means. This application is a continuationin-part of my application Serial No. 823,683, filed June 29, 1959, now abandoned.

In present day manufacturing operations many parts are made by the use of powdered metal processes. Expanding powdered metal techniques have resulted in the increased use of powdered metal parts in the industry. However, present-day equipment is virtually inoperative to produce hollow powdered metal parts and this is particularly true in those parts where the design creates axial variations from the force lines of pressing during manufacture. It is therefore a prime object of this invention to provide a process of manufacturing hollow parts of powdered metal by the utilization of a high energy charge to form the powdered metal to the desired shape.

A still further object is to provide an improved process for manufacturing powdered metal parts including the utilization of a die having a cavity adapted to support a high energy package and which upon the release of energy from the package will cause a metal powder to be compressed against the face of the cavity and to be sintered thereby forming the desired finished object.

A still further object is the provision of an improved process for manufacturing powdered metal parts including the utilization of a high energy force package which will form a powdered metal into a completed article, the said force package being constructed to provide direction- 211 control to suit the particular specifications of the powdered metal part to be formed.

A still further object is to provide a process for producing a powdered metal part, the said process including the steps of placing a plurality of powdered metal objects within a die cavity and the use of a high explosive energy package, which upon the release of a gaseous product at an explosive rate, will cause the uniting or welding of adjacent portions of the powdered articles to produce a completed powdered metal part which may be sintered during the explosion or which may be sintered immediately thereafter.

These and other objects will become more readily apparent from a reading of the description when examined in connection with the accompanying sheet of drawing.

In the drawing:

FIGURE 1 is an isometric View of a completed powdered metal article;

FIGURE 2 is a side elevational view of a die, partially in cross section, showing a cavity for forming a powdered metal article;

FIGURE 3 is a view similar to FIGURE 2 showing a die with portions thereof in cross section, and disclosing a high energy force package positioned within a quantity of powdered metal just prior to the operation of the force package;

FIGURE 4 is a side elevational view of a die showing a reinforcing and clamping structure therefor, the said figure also showing, in cross section, a portion of a cavity and a completed powdered metal article formed therein;

FIGURE 5 is an exploded view of a plurality of pow 3,165,404 Patented Jan. 12, 1965 Ice dered metal portions prior to their being united as a coinnated by the reference character 10. The die 10 comprises a' pair of die sections 11 and 12 having respectively concave walls or concavities 15 and 16. By placing the die sections 11 and 12 in the position shown in FIGURE 2, a cavity 17 is formed by the cavities 15 and 16. The cavity 17 comprises a neck 18 and a bottom 18'. The section 11 inclludes a pair of openings 19 communicating with the cavity 17. The section 12 also includes a threaded bore 19' in which a gas release pin 20 is suitably threaded. The gas release pin 20 in indicated as projecting downwardly into a cavity 17.

Referring now to FIGURE 4, the sections 11 and 12, are securely connected together by means of an upper horizontal clamp 21 having downwardly extending legs 21' suitably straddling the sections 11 and 12. Similarly a lower horizontal clamp 22 includes upwardly extending legs 22"for straddling the sections 11 and 12. A left vertical clamp 23 including horizontal legs 23' and a right vertical clamp 24 including horizontal legs 24' suitably connect and lock the clamps 21 and 22 against vertical displacement. Thus it is clear that by means of these clamps thesections 11 and 12 are securely connected together so as to be able to withstand explosive forces which may be generated within the cavity 17.

Referring now to FIGURE 3 a force package is indicated at 25, the said force package 25 being suitably connected to an electrical system (not shown) by means of electrical conductors 26 which extend outwardly from the die 10 and through the openings 19. The force package 25 is designed to produce the directional forces required for producing the part desired. dered metal 28 is disposed within the die cavity 17. In FIGURE 1 the object to be formed from the powdered metal 28 is indicated at 29.

In the operation the conductors 26 are connected to a suitable electrical detonator, as is well known in the art,

which explodes the force package 25, which in turn causes the release of hot gases at an explosive rate, and which in turn explodes and hurls the powdered metal particles against the inner walls of the cavity 17 so that they conform to the shape of the said cavity. The hot gases also serve to sinter the metal powder in the shape desired substantially simultaneously with the formation of the part. Thus the-powdered metal article 29 i formed.

The die sections 11 and 12 may be suitably connected together by the clamping means indicated or other suitable clamping means may be provided. The die sections are made of steel and generally the cavity 17 has its wall sufficiently polished as in conventional powdered metal forming. Thus the die is precision made. The die itself is a complete tool and the part 29 may be easily released by separation of the die sections 11 and 12 after the gas release pin 20 has been removed to permit the escape of v gases.

T he force package 25 may be designed to have different energy levels so a to hurl the powdered metal in different directions and exert different pressures at various given different points. The material'for the force package maybe dynamite, nitroglycerin, or any other suitable material having the ability to release gaseous pressure at explosive rates. Generally in practice the design of the force package is dependent upon the article to be formed. The

In FIGURE 3 a powa force package may be suspended within the cavity by means of wire or rod, it may be laid on the bottom of the die cavity, or it may be completely surrounded by powdered metal as shown in FIGURE 3. The exploding of the force may be done by conventional means, such as the use of a detonator ignited electrically, or by mechanical or chemical means as desired.

The release of the energy forces the powdered metal to the walls of the die. The force of the explosion compacts the metal powder in the desired shape and the heat generated by the explosion will initiate a sintering action between the particles of metal. The force is transmitted to the powdered metal as a gas, or as a shock wave and thus is exerted in all directions. Thus it is possible to form shoulders, undercuts, tapers and other irregular shapes of powdered metal material. Thus this force in all directions overcomes the limitation of conventional powdered metal presses where the force is in one direction only whereby the shape of the parts that can be manufactured are greatly limited.

In FIGURES 5, 6 and 7 a modified apparatus and process is disclosed. As shown in FIGURE 5, in an exploded fashion, cylindrical sleeve portions 30 and 31 are positioned in adjacent relation with respect to a frustoconical sleeve 32. FIGURE 6 shows a die similar to the die and thus the same reference characters will apply. However, the die 10 has an inner concavity 33 and a wall 34 which is made to conform to the contour or shape of the portions 30, 31 and 32 when they are placed with certain portions in aligned and contiguous relation. This positioning is shown in FIGURE 6, and FIGURE 7 shows the finished part after the operation of the die. A force package is designated at 35, the said force package being connected by means of conductors 36 to a suitable detonator, not shown, in the same manner as the force package 25 shown in FIGURE 3.

The operation of the modification is similar in that the force package 35 releases a hot gas at an explosive rate, this hot gas in turn causing a welding of the adjacent contiguous portions of the parts 30, 31 and 32 thereby forming the completed powdered metal parts shown in FIG- URE 7. In this case also the gas release pin 20 may be removed for removing the gas within the cavity 33.

The density of the compact or pressed powdered metal is a function of the amount of energy released from the force package. Thus also because of the high heat involved sintering will take place during the explosion. Further sintering may be obtained by heating the die to the given temperature and holding it at the temperature for the required time. In the latter event the gas pressure within the powdered metal part and within the die is not released, but is maintained during the sintering operation wherein the dies are heated.

Thus as shown in FIGURES 1, 2, 3 and 4, the powdered metal, which incidentally may be powdered iron, aluminum, etc., is formed into a completed object by means of the explosion which takes place in the chamber 17. In FIGURES 1 through 4 sintering also may occur as a result of the heat generated or may occur by means of heating of the die while gaseous pressure is maintained within the die cavity 17. In FIGURES 5, 6 and 7 separate powdered metal parts are united by means of the high pressure and heat which is involved upon the explosion of the force package 35. Adjacent portions of the separate powdered metal objects are thus welded together and sintering and a high compressed compact is efiected.

Referring to FIGURES 1 through 4 a specific example in the formation of the powdered metal part may be as follows:

The powder may be 99% Fe (iron powder) with 1% or less impurities. The density of the powdered metal may be 5.5 g./ cc. or, stated in another manner, the volume may be approximately 118% of the finished volume. After formation of the part it will have a minimum density of 80 +300. The force package utilized for creating the explosive energy may be Du Pont EL 506 explosive sheet and 6.4 sq. in. are employed. This force package will provide a force of 100,000 p.s.i. or a total of 300 tons pressure. Thus the powder will be compacted in all directions and produces a part having a minimum density of 6.5 g./cc. The explosive sheet Du Pont EL 506 is efiective and can be purchased in the open market. The exact chemistry of this explosive sheet is not known to the applicant. In order to release the explosive energy a Du Pont blasting cap known by the trade name as PETN also may be utilized.

It is estimated that. the gas which is released reaches a temper ture from l7002l00 F. which causes the sintering operation. It is believed that the extremely rapid movement of the powder particles to new positions in intimate contact with each other, is caused by the shock and gas pressure waves which will aid the generating of sintering temperature to cause atomic movement between the powder particles. This action produces the homogeneous structure. The energy in the form of a moving gas, in the confined area will be translated into heat for sintering. To augment the sintering operation the part after the release of the force package may also be placed in a furnace having a temperature between 1700 and 2l00 F. Such a furnace may be gas fired or electrical, as desired.

The same type of force package may be utilized in connection with the modification shown in FIGURE 6. The sintered parts may be composed of 99% pure iron with the remainder impurities. The heat generated by the force package will provide the additional sintering causing the welding of the parts in assembly. Thus again the high heat results from the explosive forces in release of hot gases which may be at a temperature of 1700- 2100 F.

Thus it is apparent that improved methods of manufacturing a powdered metal article have been disclosed.

It must be understood that changes in the process may be made without departing from the spirit of the invention as disclosed nor the scope thereof as defined in the appended claims.

What is claimed is:

l. A process of forming hollow articles from powdered metal in a die having an interior wall defining a hollow cavity comprising the steps of, placing a quantity of powdered metal within said cavity, said quantity being of less volume than the volume of said cavity, supporting a force package within said cavity and beneath a portion of said quantity of powdered metal, said force package being capable of releasing a hot gaseous product at an explosive rate in a direction substantially transverse to the base of said die, and releasing said gaseous product in said explosive whereby said hot gaseous product heats said powdered metal to produce sintering of the same and simultaneously compacts said powdered metal against portions of the interior wall of said die to produce a hollow powdered metal article.

2. A process of forming hollow articles from powdered metal comprising the steps of placing a quantity of powdered metal in the cavity of a die, said cavity being formed by an interior wall in said die, said powdered metal having a volume less than the volume of said cavity, supporting a force package within said quantity of powdered metal and near the bottom thereof, said force package being capable of releasing a hot gaseous product at an explosive rate in direction substantially transverse to the base of said cavity, and releasing said hot gaseous product directionally at said explosive rate whereby said powdered metal is sintered and whereby said powdered metal is simultaneously compacted in a layer against portions of said interior wall to produce a hollow powdered metal article.

3. A process of forming hollow articles from powdered metal comprising the steps of placing a quantity of powdered metal in the cavity of a die, said cavity being formed by an interior wall in said die, said powdered metal having a volume less than the volume of said cavity, supporting a force package within said powdered metal, said force package being capable of releasing a hot gaseous product at an explosive rate in predetermined directional manner substantially transverse to the bottom of said cavity, and releasing said gaseous product directionally at said explosive rate whereby said powdered metal is sintered and compacted in a layer against portions of said interior wall to produce a hollow powdered metal article.

4. A process of forming hollow articles from powdered metal comprising the steps of placing a quantity of powdered metal in the cavity of a die, said cavity being formed by an interior wall in said die, said powdered metal having a volume less than the volume of said cavity, supporting a force package within said powdered metal, said force package being capable of releasing a hot gaseous product at an explosive rate, and releasing said hot gaseous product at said explosive rate whereby said powdered metal is simultaneously compacted in a layer against portions of said interior wall to produce a hollow powdered metal article.

5. A process of manufacturing hollow powdered metal articles comprising the steps of applying pressure to powdered metal to form a plurality of loosely compacted metal parts, placing said parts in the enclosed cavity of a die, said powdered metal parts each having an opening and said parts having portions positioned in substantially contiguous relation with the openings substantially in registry, said cavity having an interior wall conforming substantially in shape to the outer shapes of the powdered metal parts, positioning a force package in the openings of said parts, said force package being capable of releas ing a hot gaseous product at an explosive rate, and releasing said hot gaseous product at said explosive rate whereby said powdered metal parts are sintered and further compacted and contiguous portions of said parts are joined as a result of the heat and pressure generated by said gaseous product.

6. A process of manufacturing hollow powdered metal articles comprising the steps of forming a plurality of loosely compacted metal parts from powdered metal, placing said parts in the enclosed cavity of a die at least one of said parts having an opening, said parts having portions positioned in substantially contiguous relation, said cavity having an interior wall conforming substantially in shape to the outer shapes of the powdered metal parts, positioning a force package in the opening of one of said parts, said force package being capable of releasing a hot gaseous product at an explosive rate, and releasingsaid gaseous product at said explosive rate whereby said powdered metal parts are further compacted and sintered and contiguous portions of said parts are joined as a result of the heat and pressure generated by said gaseous product.

7. A process of manufacturing hollow powdered metal articles comprising the steps of placing a plurality of loosely compacted and preformed powdered metal parts in the enclosed cavity of a die, at least one of said parts having an opening, said parts having portions positioned in substantially contiguous relation, said cavity having an interior wall conforming substantially in shape to the outer shapes of the powdered metal parts, positioning a force package in the opening of one of said parts, said force package being capable of releasing a hot gaseous product at an explosive rate, and releasing said gaseous product at said explosive rate whereby said parts are further compacted and said contiguous portions of said parts are joined as a result of the heat and pressure generated by said gaseous product.

8. A process of manufacturing hollow powdered metal articles comprising the steps of placing a plurality of loosely compacted powdered metal parts in an enclosed cavity of a die in a manner wherein said parts have edge portions positioned in contiguous relation, said parts having outer sides conforming generally to the configuration of said cavity, placing a force package within the cavity, said force package being capable of releasing a hot gaseous product at an explosive rate, and releasing said but gaseous product at said explosive rate whereby said parts are further compacted and said edge portions are joined by the heat and explosive pressure to provide a unitary hollow powdered metal article.

9. A process of manufacturing powdered metal articles comprising the steps of placing a plurality of powdered metal parts in an enclosed cavity of a die in a manner wherein said parts have edge portions positioned in contiguous relation, placing a force package within the cavity, said force package being capable of releasing a hot gaseous product at an explosive rate, and releasing said gaseous product at said explosive rate whereby said edge portions are joined to provide a unitary powdered metal article.

References Cited in the file of this patent UNITED STATES PATENTS 2,978,796 Kemeny Apr. 11, 1961 3,023,462 Taylor et a1. Mar. 6, 1962 3,036,373 Drexelius May 29, 1962 

1. A PROCESS OF FORMING HOLLOW ARTICLES FROM POWDERED METAL IN A DIE HAVING AN INTERIOR WALL DEFINING A HOLLOW CAVITY COMPRISING THE STEPS OF, PLACING A QUANTITY OF POWDERED METAL WITHIN SAID CAVITY, SAID QUANTITY BEING OF LESS VOLUME THAN THE VOLUME OF SAID CAVITY, SUPPORTING A FORCE PACKAGE WITHIN SAID CAVITY AND BENEATH A PORTION OF SAID QUANTITY OF POWDERED METAL, SAID FORCE PACKAGE BEING CAPABLE OF RELEASING A HOT GASEOUS PRODUCT AT AN EXPLOSIVE RATE IN A DIRECTION SUBSTANTIALLY TRANSVERSE TO THE BASE OF SAID DIE, AND RELEASING SAID GASEOUS PRODUCT IN SAID EXPLOSIVE WHEREBY SAID HOT GASEOUS PRODUCT HEATS SAID POWDERED METAL TO PRODUCE SINTERING OF THE SAME AND SIMULTANEOUSLY COMPACTS SAID POWDERED METAL AGAINST PORTIONS OF THE INTERIOR WALL OF SAID DIE TO PRODUCE A HOLLOW POWDERED METAL ARTICLE. 